This brings down StdlibUnittest build time to 90 seconds with either
a DebugAssert or a ReleaseAssert compiler.
The new library, StdlibCollectionTests, is only built when running
validation tests.
Fixes:
* multiple statements on one line (colon) (E701)
* missing whitespace around arithmetic operator (E226)
* missing whitespace around operator (E225)
* closing bracket does not match visual indentation (E124)
* blank line contains whitespace (W293)
* continuation line missing indentation or outdented (E122)
* continuation line over-indented for hanging indent (E126)
* missing expected blank line (E301)
* trailing whitespace (W291)
* unexpected spaces around keyword / parameter equals (E251)
* whitespace after '(', '[' or '{' (E201)
* whitespace before ')', ']' or '}' (E202)
* whitespace before ',' or ':' (E203)
Fixes:
* blank line at end of file
* closing bracket does not match indentation of opening bracket's line
* continuation line over-indented for hanging indent
* continuation line over-indented for visual indent
* continuation line unaligned for hanging indent
* inline comment should start with '# '
* missing whitespace around arithmetic operator
* missing whitespace around bitwise or shift operator
* multiple imports on one line
* multiple spaces after ':'
* multiple spaces after operator
Rather than using `f = open(path).read()`, which leaves the file open
for an indeterminate period of time, switch to the `with open(path) as f`
idiom, which ensures the file is always closed correctly.
